[llvm-dev] LLVM Weekly - #252, October 29th 2018

[Alex Bradbury via llvm-dev]

LLVM Weekly - #252, October 29th 2018
=====================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/252>.

Welcome to the two hundred and fifty-second issue of LLVM Weekly, a weekly
newsletter (published every Monday) covering developments in LLVM, Clang, and
related projects. LLVM Weekly is brought to you by [Alex
Bradbury](https://www.linkedin.com/in/alex-bradbury/). Subscribe to future
issues at <http://llvmweekly.org> and pass it on to anyone else you think may
be interested. Please send any tips or feedback to <asb at asbradbury.org>, or
@llvmweekly or @asbradbury on Twitter.


## News and articles from around the web

Stephen Kelly has published blog posts on [extending
clang-tidy](https://blogs.msdn.microsoft.com/vcblog/2018/10/19/exploring-clang-tooling-part-1-extending-clang-tidy/)
and [examining the Clang AST with
clang-query](https://blogs.msdn.microsoft.com/vcblog/2018/10/23/exploring-clang-tooling-part-2-examining-the-clang-ast-with-clang-query/).


## On the mailing lists

* Alexander Ivchenko posted an RFC on [implementing asm-goto support in Clang
and LLVM](http://lists.llvm.org/pipermail/llvm-dev/2018-October/127239.html).
One of the main motivations is to support the GCC inline assembly extension
used by the Linux kernel. But the mechanism is more general and may support
control flow tracking for setjmp/longjmp, or intrinsics with multiple
successors (such as an [atomic cmpxchg primitive lowered to ll/s with two
successor
blocks](http://lists.llvm.org/pipermail/llvm-dev/2018-October/127242.html)).

* Graham Hunter
[reports](http://lists.llvm.org/pipermail/llvm-dev/2018-October/127226.html)
that he has posted a proposal for scalable vector types [to
Phabricator](https://reviews.llvm.org/D53695).

* Kristof Beyls
[summarised](http://lists.llvm.org/pipermail/llvm-dev/2018-October/127225.html)
the discussion from the LLVM bug cycle Birds of a Feather session at the LLVM
Dev Meeting.

* Reid Kleckner
[proposes](http://lists.llvm.org/pipermail/llvm-dev/2018-October/127140.html)
moving llvm.dbg.value out of the instruction stream.

* James Y Knight
[continues](http://lists.llvm.org/pipermail/llvm-dev/2018-October/127139.html)
to work on the new git canonical LLVM git repository. Although the intent is
to mark it "final" as soon as possible, I haven't seen that declaration yet.
Therefore, now is the time to jump in and check for any issues.

* Anastasia Stulova
[summarised](http://lists.llvm.org/pipermail/cfe-dev/2018-October/059974.html)
the LLVM Dev Meeting round table discussion on SPIR-V. The preference from the
developers attending that meeting was to continue development of the SPIR-V
translation tool.


# LLVM commits

* The AArch64 backend gained a new pass to compress jump-table entries when
possible. [r345188](https://reviews.llvm.org/rL345188).

* Documentation and a script were added for building clang+LLVM with PGO.
[r345247](https://reviews.llvm.org/rL345247).

* The bisect-skip-count utility gained documentation.
[r344903](http://reviews.llvm.org/rL344903)

* New `FMINNUM_IEEE/FMAXNUM_IEEE` SelectionDAG nodes were introduced to
perform floating-point min/max following the IEEE-754 2008 definition.
[r344914](https://reviews.llvm.org/rL344914).

* FixedLenDecoderEmitter can now use APInt-like objects as InsnType, useful
for targets where `uint64_t` is not sufficient for encoded instructions.
[r345056](https://reviews.llvm.org/rL345056).

* A list of potential benchmarks for the LLVM test-suite has been committed.
[r345074](https://reviews.llvm.org/rL345074).


## Clang commits

* Clang command-line options were added for AArch64 branch protection and
return address signing. [r345273](https://reviews.llvm.org/rL345273).

* Function multiversioning is now supported non-ELF systems.
[r345298](https://reviews.llvm.org/rL345298).


## Other project commits

* libcxx gained a benchmark for std::set.
[r345035](https://reviews.llvm.org/rL345035).

* The `OUTPUT_FORMAT` linker script directive is now supported by lld.
[r344952](https://reviews.llvm.org/rL344952).